1. Field of the Invention
One embodiment of the present invention relates to a display device, a display module, and an electronic device.
Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. The present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a storage device, a driving method thereof, or a manufacturing method thereof.
2. Description of the Related Art
Mobile devices such as smartphones and tablets have become increasingly popular. In addition, novel devices such as head-mounted displays and digitized car-mounted display devices have been used, and high visibility and low power consumption are required.
An active-matrix organic EL display employs a hold-type display method (hereinafter referred to as hold-type driving) that features high response speed, a wide viewing angle, and the like. In hold-type driving, a light-emitting element emits light during one frame period (one frame is a unit of an image to be displayed). Luminance during one frame period is added up as emission luminance to control gradation. For example, in a display device that displays 60 frames for one second, an image is displayed 60 times for one second. In that case, one frame period is approximately 16.67 ms.
Another driving method is an impulsive display method (hereinafter referred to as impulsive driving). In impulsive driving, light is emitted during a selection period of a pixel circuit at the same luminance as total luminance during one frame period to control gradation.
Note that in hold-type driving or impulsive driving, a voltage set method where emission luminance is set by voltage and a current set method where emission luminance is set by current are known.
Although the response speed of an organic EL element is higher than that of a liquid crystal element, a moving image blur that causes a decrease in the resolution of moving images is generated in displaying moving images in hold-type driving. The resolution of moving images refers to visual resolution in displaying moving images and resolution that is perceived by a person in displaying moving images. For example, the resolution of moving images refers to the limiting resolution at which the updating interval of images can be recognized in the case where a wedged figure is scrolled on a screen.
For example, in Patent Document 1, a control method for increasing visibility by controlling gradation with a combination of impulsive driving and hold-type driving has been proposed.
For example, in Patent Document 2, a method for improving the resolution of moving images by inserting a black frame between display frames has been proposed, and a method for suppressing a decrease in lifetime of an organic EL element by decreasing the light emission period of the organic EL element has been disclosed.